ERRORS ATTRIBUTED TO ARISTOTLE. 193 



garded the left auricle also as a mere part of the " arte- 

 ria venosa." The canal which leads from the right cav- 

 ity of the heart to the lung (or, as Aristotle puts it (E), 

 from the lung to the heart) is, without doubt, the pul- 

 monary artery. But it may be said that, in this case, 

 Aristotle contradicts himself, inasmuch as in (P) and 

 (Q) a vessel, which is obviously the pulmonary artery, is 

 described as a branch of the great vein. However, this 

 difficulty also disappears, if we reflect that, in Aristotle's 

 way of looking at the matter, the line of demarcation 

 between the great vein and the heart coincides with the 

 right auriculo-ventricular aperture; and that, inasmuch 

 as the conical prolongation of the right ventricle which 

 leads to the pulmonary artery (R.v f in the Figure), lies 

 close in front of the auricle, its base may very easily (as 

 the figure shows) be regarded as a part of the general 

 opening of the great vein into the right ventricle. In 

 fact, it is clear that Aristotle, having failed to notice the 

 valves of the heart, did not distinguish the part of the 

 right ventricle from which the pulmonary artery arises 

 (R.v r ) from the proper trunk of the artery on the one 

 hand, and from the right auricle (fi.a.) on the other. 

 Thus the root, as we may call it, of the pulmonary artery 

 and the right auricle, taken together, are spoken of as 

 the "part of the great vein which extends upwards" 

 (P)] and, as the vena azygos (As) was one branch of 

 this, so the " vein to the lung " was regarded as another 

 branch of it. But the latter branch, being given off 

 close to the connection of the great vein with the ven- 



